Abstract
BackgroundThe clinical utility and prognostic impact of presumed primary breast or ovarian cancer among patients with an unfavorable subset of cancer of unknown primary site (CUP) remains unclear. We aimed to evaluate the clinical relevance of the presumed primary site of CUP and the clinical outcome of site-specific therapy based on such presumptions.MethodsPatients referred to our center who were diagnosed with unfavorable-subset CUP and treated between April 2007 and March 2015 were enrolled in this study. Data were collected retrospectively from the hospital database and electronic medical records. Presumptive primary breast or ovarian cancer was based on histological and immunohistochemical analyses and metastatic patterns. The outcomes of patients with unfavorable-subset CUP with a putative primary site in the breast or ovary (P-CUP) and of patients with unfavorable-subset CUP, but without P-CUP (U-CUP), were assessed.ResultsA total of 780 patients were referred to our hospital with malignancy of unknown origin. Of these, 409 patients were diagnosed with CUP and 344 patients with unfavorable-subset CUP. Following clinicopathological examination, 40 (11.6%) of the 344 patients had P-CUP and the remaining 303 (88.3%) patients had U-CUP. In total, 136 patients received chemotherapy (22 with P-CUP and 114 with U-CUP). Among the 22 patients with P-CUP, three received hormonal therapy for breast cancer, and 19 received chemotherapy based on the presumed primary organ (breast, 4; ovaries, 15). Conventional platinum-based chemotherapy was administered to 105 patients with U-CUP and non-platinum drug treatment to nine patients. The objective response rates were 61.1% (95% confidence interval [CI]: 38.6–83.6) and 41.1% (95% CI: 31.8–50.4) for patients with P-CUP and U-CUP, respectively. The median overall survival durations were 50.0 months and 16.9 months (log-rank: P = 0.002) for patients with P-CUP and U-CUP, respectively. P-CUP was identified as an independent predictor of good prognosis according to multivariate analysis.ConclusionsPatients with P-CUP had higher response rates and a better prognosis compared with patients with U-CUP. It might thus be reasonable to classify this subset as a new category of CUP with a favorable prognosis.
Highlights
The clinical utility and prognostic impact of presumed primary breast or ovarian cancer among patients with an unfavorable subset of cancer of unknown primary site (CUP) remains unclear
We aimed to review the diagnostic outcomes of malignancy of unknown origin (MUO) and the clinical outcomes of patients with unfavorable-subset CUP who received chemotherapy at the National Cancer Center Hospital in Japan
Diagnosis of malignancy of unknown origin A total of 780 consecutive patients with suspected MUO were evaluated during the study period
Summary
The clinical utility and prognostic impact of presumed primary breast or ovarian cancer among patients with an unfavorable subset of cancer of unknown primary site (CUP) remains unclear. It is essential to identify and/or predict the primary site for all advanced cancer patients who present with metastatic disease in whom the diagnosis of the primary site is uncertain at the time of referral to the oncologic department. Patients in the favorable subset have a favorable response to specific treatments, and are defined by their clinical course, metastatic pattern, and pathologic features [8] These patients are treated with an approach appropriate for the presumed primary site. Those patients could benefit from the presumptive diagnosis of the primary site by pathological and molecular diagnostic techniques, potentially making them eligible for new and effective therapies for specific cancers. Patients with presumed primary breast or ovarian cancer with diffuse metastatic disease remained in the unfavorable subset
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